I plan to buy the new Nuc5i7RYH. I have a 2.5' hard drive that has window 7 pre-installed. It was the hard drive that came with my Dell Studio XPS 1647 laptop. I have currently replaced it with a Samsung ssd. I would like to ask some questions.

1. Can I use this hard drive in the Nuc without reformatting the hard drive and reinstalling window 7 ?

2. From the product support page, it states that Nuc5i7RYH supports DDR3L 1.35 V DDR3L (low voltage) SO-DIMMs 1333 MHz or 1600 MHz. However, in the tested memory section, it states that it passed testing for some of the DDR3L SO-DIMMs 1866 MHz. Does this Nuc support 1866 MHz ?

I am not from Intel, but #3 should work (I do it on NUC5i5RYH). #1 typically does not work as you'd like - certainly the Windows would no longer be activated and presumably activation would be difficult since it was Dell OEM (rather than retail). There may also be driver issues, one of the most important might be the disk driver such as RAID and/or AHCI mode. For #2, I think that certain 1866 may work but the last couple generations of NUC have been somewhat sensitive to memory compatibility such as the "density" of the memory (related to how many chips per side of the SO-DIMM). I am using some 1866 in my NUC5i5RYH (HX318LS10IBK2/8).

Thank you for posting your questions here so we can share these details with you and all community.

You can use the SSD on the NUC without reformatting it. There is a chance that it may boot but it is not recommendable to do this because you may encounter some unexpected behaviors since there are no correct drivers installed.

As you mentioned before, the NUC can handle that type of memory and it can use up to 1866MHz.

In regards to using the SATA port and M.2 yes, you can do this. It is possible to use both devices at the same time.

Generally, you want to have the drivers installed in the OS prior to powering on, AND sometimes the formatting from the prior system may not be optimal for the NUC.

I tend to use Acronis True Image, which allows you to backup the system drive in question, and then restore it. (It has the ability to create multiple types of boot media for doing this, and even has a utility that will slip drivers into a Windows OS so that you can migrate it!)

You do need to have an idea as to what you are doing, but once you backup the drive in question. You can restore and many times as it takes...

Technically it is possible. I transplanted a Bootcamp partition from an Apple Mac mini to a SSD in the NUC:

I made a backup with Paragon Hard Disk Manager Suite 14 from the Bootcamp partition. On the NUC I made a dummy install of Windows to get the correct partition layout. Then I restored the backup from a bootable USB PHDMS 14 stick to the NUC. I used Paragon's built in Adaptive Restore to implant the correct drivers for the NUC machine. To my astonishment it then booted. But with a lot of drivers still missing (Ethernet, Network, Audio, USB 3.0 and some more). I downloaded all the neccessary drivers from Intel, then only the network driver still iwas missing. After a deinstallation of this device and its drivers and a rerun of the appropriate Intel drivers everything works as before.

I had to reactivate Windows unfortunately. The original poster probably would have to buy a new license.